Fingerprints are well understood to be unique to an individual and are therefore useful for identification and verification purposes. The surface asperities (that is, the ridges and valleys) that constitute a fingerprint can be sensed and imaged in a variety of ways and used thereafter to compare with previously stored fingerprint information for these purposes. Unfortunately, these prior art methods and apparatus are not suitable for all purposes.
Inked fingerprint patterns can be inspected and compared by a skilled person but this process requires considerable training and potentially requires significant amounts of time and resources. Such an approach is also inappropriate for dispersed automatic identity verification applications. Thermal sensing mechanisms exist to capture fingerprint asperities but such mechanisms tend to be expensive to manufacture and further typically require complicated (and therefore costly) correlation software to make beneficial use of the results. Radio frequency based mechanisms exist that utilize an active antenna array to penetrate the subdermal layer of the finger with a radio frequency signal to thereby detect the asperities. While such mechanisms are extremely accurate they are also extremely expensive and typically represent an investment of thousands of dollars.
Capacitance based mechanisms again offer relatively good asperity detection but are susceptible to electrostatic discharge that can impair or destroy the mechanism. Although such mechanisms can be made small (such that they are of useful size for many automatic verification applications), many such mechanisms must utilize titanium oxide materials to protect against such electrostatic discharge and this significantly raises the cost of the resultant mechanism. Furthermore, such capacitance based mechanisms again typically require a considerable amount of processing capability to convert the sensed asperities into storable data.
Optical based solutions using a solid-state camera and a light emitting diode as a light source are presently achieving some widespread usage, particularly for portable automatic verification applications. While optical based solutions function reasonably well under many operating conditions, these solutions have form factor requirements (to accommodate, for example, necessary focal length for the camera) that make them unsuitable for many uses. Furthermore, while the cost of such devices (presently about $130 per unit) is relatively favorable as compared to other available technologies, this price is still too high for many desired applications.
A need therefore exists for an asperity sensing and storage solutions that at least minimizes some of these various problems and challenges. In particular, a need exists for a cost-effective, reliable, form factor friendly solution that does not place undue processing demands upon corresponding support hardware and software.